It is advantageous to be able to automatically read identification data on a vehicle in order to automatically recognize from a list whether or not the vehicle counts as a subscriber for which access is authorized with payment being performed automatically by debiting an account held by the operating company or by paying a flat fee in advance when taking out the subscription.
The invention also applies to capturing vehicle identification data and storing the time of arrival in a car park or at an entrance to a motorway together with the identification data in order to calculate an amount to be paid on exit at a point-of-sale terminal having access to said stored data.
The characteristic data for identifying a vehicle is naturally constituted by its number plate.
For the operator of a pay car park or toll motorway, the advantage of using number plates as vehicle identification data lies in the fact that there is no need to invent a special characteristic code since such a code already exists, is very reliable, and is, in addition, highly dissuasive of attempts at fraud by small-time cheats.
However, in order to avoid slowing down arrivals, the numbers must be read automatically very quickly, and in practice they must be read on vehicles which are moving.
In this respect, it is a computationally long and difficult task to read a number plate and in particular to identify it and distinguish it from the other written matter which is often present on the rear of a vehicle, e.g. stickers with various messages.